Glider Manufacturers
The number of glider manufacturers has declined over the years. Although Wikipedia lists pretty much everyone who has ever made a glider, I'm only going to list companies here that are currently producing gliders or supporting gliders they've made.
DG Flugzeugbau in Bruchsal, Germany. I had the chance to tour their very spacious, modern factory during the summer of 2012 with some German glider friends, coworkers, and CAP Cadets.
Jonkers Sailplanes are produced in South Africa and becoming increasingly more popular.
Schemp-Hirth Flugzeugbau is located in the town of Kirchheim (Teck), Germany not too far from the historic Hahnweide glider field where I flew for two years.
Alexander Schleicher is in Poppenhausen, Germany, not far from the well known and historic Wasserkuppe where I did my initial German aerobatic training. On a rainy day during the aerobatic course we had a chance to tour the factory. I saw the mold that every ASK-21 I've flown came out of!
American Windward Performance is a new glider manufacturer, but has had good luck so far.